This article will describe the process of stripping paint from a miniature using Acetone.

Acetone is cheap (I paid 5 euro for 1 liter) and quite easy to work with. Always use acetone in a well ventilated place, make sure you don't waste anything in the sink, on the ground, and keep the product away from children, pets, ...

I bought a bottle of acetone in a DIY store, you can find this product usually where other liquids like ammonia, white spirit and brush cleaner are.

Don't be fooled by the fact that acetone is often packed in a plastic bottle. The liquid and also the fumes will melt away most plastics, including those used in our hobby, both on models and bases. This makes it unusable for plastics. I haven't tried it on resin though.
This is the victim. Before submerging her into the acetone I removed the base.

Use a glass jar with a metal lid for the stripping process. A shallow jar is easier to retrieve the miniature. Put the figure in the jar (or more than one in one go), and pour a couple of centimeters over it.Please notice I am doing this above the sink in my garage. By no means do this in your kitchen or anything. If you don't have a garage do this outside.

Now leave it to soak. How long is up to you and also depends on the paintjob on the miniature: is it covered in a thick layer of paint and/or primer? Is it only lightly basecoated? In my case the figure got an intermediate coat of white primer and some thin layers of paint.
Even minutes after putting it in the liquid I saw paint flaking off. So this stuff is quite violent to the painted surface. So my guess is, if you're in a hurry, you can already take out the figure after 30 minutes, or maybe less. I left mine to soak for 8 hours, but I assume there isn't much difference between a 4 hour soak or an overnight one. A lof of the primer has also dissolved by now:

Take the figure out of the jar with some pliers or tongs. Put it under some running water. Seeing the picture now makes me realize I'd better put a bucket or something in the sink. This is a must when working with small parts. You don't want any of those washing down the drain.

The result after the soak and the rinsing with water:

Now give it a good rub with a toothbrush, under lukewarm water and with some dishwashing fluid. The final result is quite surprising, all the primer came off. Only in the deepest recesses there is some paint left. If you want you can try to fiddle that out with a needle or something, but usually this won't be noticed when painting.